The Collaborative International Dictionary of English v.0.48:

Tacky \Tack"y\, a. [Cf. Techy, Tack a spot.]
   Sticky; somewhat adhesive;; -- said of paint, varnish, etc.,
   when not well dried. [U. S.]
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Tacky \Tack"y\, a. [Etymol. uncert.]
   1. Dowdy, shabby, or neglected in appearance; unkempt.
      [Local, U. S.]
      [Webster 1913 Suppl.]

   2. In poor taste; appearing cheap; gaudy; unstylish. Broadly
      used to describe objects whose style is disapproved of by
      the speaker.
      [PJC]

   3. Tactless; in poor taste; -- used to describe behavior.
      [PJC]

The Collaborative International Dictionary of English v.0.48:

Tacky \Tack"y\, n. [Written also tackey.]
   An ill-conditioned, ill-fed, or neglected horse; also, a
   person in a like condition. [Southern U. S.]
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

tacky
    adj 1: (of a glutinous liquid such as paint) not completely
           dried and slightly sticky to the touch; "tacky varnish"
    2: tastelessly showy; "a flash car"; "a flashy ring"; "garish
       colors"; "a gaudy costume"; "loud sport shirts"; "a
       meretricious yet stylish book"; "tawdry ornaments" [syn:
       brassy, cheap, flash, flashy, garish, gaudy,
       gimcrack, loud, meretricious, tacky, tatty,
       tawdry, trashy]